It all adds up

I find doing two things at once is tough at the best of times, but when one of those things is mental arithmetic - well, you can count me out.

Which might make you think that KooZac was on to a non-starter with this numerically challenged hack. After all, it's built on the premise of combining a Tetris-style puzzler with a Sudoku-like maths challenge.

Fortunately, it's not quite as dry as it sounds.

Numbers up

It goes a little something like this: coloured blocks, each containing a number, drop from the top of the screen. You have to match up two or more number blocks so that they add up to the featured number at the top of the screen.

Do this and the blocks disappear, giving you points. You get bonus points for matching up blocks of the same colour or number.

That's the core premise, and in truth it's a little dull to start with. Fortunately, there are a couple of tweaks that lift it to something approaching compelling.

Mental block

First up, there are the different modes. Puzzle mode is the main one, and it gives you a series of preset block arrangements. You have to take out these special silver blocks in order to proceed.

Then there's Blitz mode, which tasks you with matching as many blocks as possible within a minute. The twist is that you can play this mode competitively with your Facebook buddies.

But the real star here is the boosters that you can buy. These change the rules in different ways for a couple of rounds. Our favourite is the one that allows you to make the numbers add up sideways as well as in the normal vertical way.

Bit of a nerd

These little touches elevate KooZac above average, but only just. It's a pretty flat, plain-looking game with minimal adornment and some fairly dull music. Or should I say 'muZak'?

There's also no denying the fact that the core mechanic of sliding blocks around and adding up is hardly going to set the heart racing.

KooZac, then, is like your favourite maths teacher - good at its job and interesting enough to spend an hour or two per day with. But at the end of the day, you wouldn't necessarily rush to tell your friends about it.